Synaptic alterations in CA1 in mild Alzheimer disease and mild cognitive impairment

To evaluate the total number of synapses in the stratum radiatum (str rad) of the human hippocampal CA1 subfield in individuals with mild Alzheimer disease (mAD), mild cognitive impairment (MCI), or no cognitive impairment (NCI) and determine if synapse loss is an early event in the progression of the disease.

Short postmortem autopsy tissue was obtained, and an unbiased stereologic sampling scheme coupled with transmission electron microscopy was used to directly visualize synaptic contacts.